Method of configuring and updating connection identifier in a broadband wireless access communication system

ABSTRACT

In a method of configuring connection identifier (CID) update information in a broadband wireless access (BWA) communication system where each service between an mobile station (MS) and a base station (BS) has a unique CID, a registration request message is received from the MS, requesting updating of at least one old CID used for the MS. The CID update information is configured to include a bitmap area indicating whether a service corresponding to the at least one old CID is available, and a new CID area including at least one new CID in correspondence with a predetermined bit value in the bitmap area.

PRIORITY

This application is a continuation of application Ser. No. 12/099,313,filed Apr. 8, 2008, which is a continuation of application Ser. No.11/159,534, now U.S. Pat. No. 7,428,227, issued on Sep. 23, 2008, whichclaims priority under 35 U.S.C. §119 to an application entitled “Methodof Configuring and Updating Connection Identifier in a BroadbandWireless Access Communication System” filed in the Korean IntellectualProperty Office on Jun. 23, 2004 and assigned Serial No. 2004-47321, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method of configuring andupdating connection identifier (CID) information in a broadband wirelessaccess (BWA) communication system, and in particular, to a method ofconfiguring and updating a CID on a service-flow-by-service-flow basisbetween a base station (BS) and a mobile station (MS).

2. Description of the Related Art

Today's development of communication technology has been increasing userdemands for higher-speed transmission/reception of larger volumes ofdata. In this context, the Institute of Electrical and ElectronicsEngineers (IEEE) 802.16 standardization group is performing studies toprovide BWA services to MSs.

The IEEE 802.16 standard specifies high-speed datatransmission/reception schemes for MSs.

An MS transmits and receives data by connecting at least one service toa BS. A plurality of service connections are identified by theirspecific CIDs.

During setup of a new service connection between the MS and the BS, theBS allocates a CID that identifies the service connection to the MS.Service CIDs must have unique values so that they can be accuratelydistinguished within one cell under the BS. Hence, the use of a CID isconfined to one cell, and the CID can be used in setting up anotherservice connection in another cell.

In the case where the MS moves from an old cell to a new cell, or whenthe MS updates all existing service connections with a serving BS andre-registers with the serving BS in the BWA communication system, thenew BS or the serving BS allocates a new CID for each service connectionto the MS. During a handover to the new BS or reconnection to theserving BS, the MS receives the new CID from the new BS or the servingBS by a medium access control (MAC)-layer management message.

In the conventional process a new CID is allocated to the MS; that is, aCID is updated for the MS in the following way. The BS transmits to theMS CID update information including existing CIDs and new CIDs inordered pairs. The transmission of the existing CIDs is unnecessary andcauses a waste of radio resources. If the MS uses a large number ofCIDs, the volume of CID update information is large. Moreover, if alarge amount of CID update information is issued for a plurality of MSs,the overall BWA communication system suffers from a significant decreasein the efficiency of radio resources at connection updates.

SUMMARY OF THE INVENTION

An object of the present invention is to substantially solve at leastthe above problems and/or disadvantages and to provide at least theadvantages described below. Accordingly, an object of the presentinvention is to provide a method of configuring smaller-size CID updateinformation in a BWA communication system.

The above objects are achieved by providing a method of configuring andupdating CIDs in a BWA communication system.

According to one aspect of the present invention, in a method ofupdating CID information in a BS of a BWA communication system, the BSarranges at least one first CID already allocated to an MS in apredetermined order, determines whether a second CID is allocated tosubstitute for the at least one first CID, maps the at least one firstCID to a bit value in a bitmap according to the determination andincluding the bitmap in CID update information, and completes the CIDupdate information by including the second CID in correspondence withthe bit value in the bitmap.

According to another aspect of the present invention, in a CID updateinformation configuration for updating service connections between a BSand an MS in a BWA communication system where CIDs are set on aservice-flow-by-service-flow basis, first CID information includes fieldinformation in which the position of at least one first CID allocated tothe MS before connection updating is mapped in a bitmap, and second CIDinformation includes at least one second CID newly allocated to the MSbased on the bitmap.

According to a further aspect of the present invention, in a method ofconfiguring CID update information in a BWA communication system whereeach service between an MS and a BS has a unique CID, a registrationrequest message is received from the MS, requesting updating of at leastone old CID used for the MS. The CID update information is configured toinclude a bitmap area indicating whether a service corresponding to theat least one old CID is available, and a new CID area including at leastone new CID in correspondence with a predetermined bit value in thebitmap area.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 illustrates an example of the mapping relationship betweenservices and CIDs in a BWA communication system;

FIG. 2 illustrates a typical data format of CID update informationprovided to an MS in the BWA communication system;

FIG. 3 illustrates the data format of CID update information provided toan MS in a BWA communication system according to the present invention;and

FIG. 4 is a flowchart illustrating a CID updating method between a BSand an MS in the BWA communication system according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be described hereinbelow with reference to the accompanying drawings. In the followingdescription, well-known functions or constructions are not described indetail since they would obscure the invention in unnecessary detail.

In the following description, a typical CID updating method and theconfiguration of typical CID update information will precede anembodiment of the present invention. As to terms used herein, “firstCID” refers to a CID that identifies a service connected between an MSand an old BS, and “second CID” refers to a CID that a new BS allocatesto the MS. In the case where the MS is to update an existing CIDassociated with the old BS, the old BS may allocate a second CID to theMS, or as the MS hands over to a new BS, the new BS may allocate thesecond CID to the MS. An example is provided for the latter case.

FIG. 1 illustrates an example of the mapping relationship betweenservices and CIDs in a BWA communication system.

Referring to FIG. 1, an MS receives CID information from a BS to therebyidentify packets, service-flow-by-service-flow. The MS receives threeservices 10, 65 and 121 identified by CIDs 138, 239 and 23, respectivelyfrom an old BS 100.

As the MS moves from the old BS 100 to a new BS 200, the CIDs 138 and 23are changed to 4 and 124, respectively, in a CID updating operation ofthe new BS 200. In the example illustrated in FIG. 1, the service withthe CID 239 is not serviced in the new BS 200, that is, the serviceconnection is terminated. Thus, the CID 239 is released. The MS, whichhas handed over to the new BS 200, is now receiving the services 10 and121 with the updated CIDs 4 and 124, respectively from the new BS 200.

FIG. 2 illustrates a typical format of CID update information providedto an MS in the BWA communication system.

Now, referring to FIGS. 1 and 2, CID update information 20 (CID_Update)has type-length-value (TLV) encoding fields. A Value field 21 isconfigured to have first CIDs (Old_CID) and second CIDs (New_CID) in theform of TLVs.

Table 1 below illustrates the TLV encoding format of CID_Update andTable 2 below illustrates the TLV encoding format of the first andsecond CIDs.

TABLE 1 Name Type (1 byte) Length (1 byte) Value (Variable) CID_Update16 Variable Compound

TABLE 2 Name Type (1 byte) Length (1 byte) Value (Variable) New_CID 16.12 CID after handover Old_CID 16.2 2 CID before handover

The values of Types in Table 1 and Table 2 are set in compliance withthe IEEE 802.16 standards. Each of first and second CIDs is representedby 1-byte Type, 1-byte Length, and 2-byte CID information, having atotal of 4-bytes of information.

First and second CIDs encoded in the manner illustrated in Table 1 andTable 2 are set in the Value field 21 such that a first CID 25 & asecond CID 23 and a first CID 29 & a second CID 27 are arranged in pairsfor corresponding services. In the case of typical CID_Updateillustrated in FIG. 2, for example, when two CIDs are updated, the Valuefield 21 has a total of 16-bytes of information. Therefore, thetransmission of the first CIDs along with the second CIDs causes a wasteof radio resources.

Accordingly, the present invention provides a method of modifying theconfiguration of the CID update information to minimize the amount offirst CID information included in the CID update information. Morespecifically, the new BS 200 compresses the entire first CIDs allocatedby the old BS 100 in the form of a bitmap. To do so, the new BS 200arranges the first CIDs in a predetermined order (i.e. ascending ordescending order) of CID value and indicates in the bitmap whether thefirst CIDs have been updated or not. The arrangement order can be theorder of allocating the first CIDs by the old BS 100, the order ofrecognizing the first CIDs by the new BS 200, or a predetermined order.

In updating the first CIDs allocated by the old BS 100, the new BS 200sets bit values at positions corresponding to the arranged first CIDs to1s if the new BS 200 can allocate second CIDs to substitute for thefirst CIDs. However, if a service provided by the old BS 100 is notavailable to the MS in the new BS 200 (for example, the service with afirst CID of 239 in FIG. 1) the new BS 200 sets a bit value at aposition corresponding to the position of the first CID to 0, to therebyindicate whether the services with the CIDs used with the old BS 100 aresuccessfully updated in the new BS 200.

By configuring a first CID field in the new CID update information inthis way, the first CIDs are represented in a bitmap. New CIDssubstituting for old CIDs having a bit value of 1 from the leastsignificant bit (LSB) to the most significant bit (MSB) of the bitmapare arranged successively in the TLV encoding format, following thebitmap. In this manner, the new CID update information is completelyconfigured, which will be described in greater detail in reference toFIG. 3.

FIG. 3 illustrates the data format of the CID update informationprovided to an MS in a BWA communication system according to the presentinvention.

Referring to FIGS. 1 and 3, new CID update information 30 (CID_Update)of the present invention is composed of a plurality of TLV fields. TheseTLV fields are divided into an Old_CID_BITMAP area 33 representingservices which have CIDs allocated by the old BS and are also availablein the new BS, as a bitmap code of first CIDs, and New_CID areas 35 and37 sequentially representing new CIDs corresponding to bit value 1 inthe Old_CID_BITMAP area 33.

Table 3 below illustrates an example of encoding the CID updateinformation 30, and Table 4 below illustrates an example of encoding theOld_CID_BITMAP 33, New_CID 35, and New_CID 37.

TABLE 3 Name Type (1 byte) Length (1 byte) Value (Variable) CID_Update16 Variable Compound

TABLE 4 Type (1 Length (1 Name byte) byte) Value (Variable) New_CID 16.12 CID after handover Old_CID_BIT 16.4 Variable The first one byteindicates the MAP length of the following BITMAP in bytes. The n-th MSBof the BITMAP set to 1 when the n-th old CID is successfully updated tonew one. Where, the old CIDs are sorted with increasing order. After theBITMAP, a list of new CID follows. The number of new CID is equal to thenumber of ‘1’ in the BITMAP.

The values of Types except for Old_CID_BITMAP in Table 3 and Table 4 areset in compliance with the IEEE 802.16 standards. Each of second CIDs 35and 37 is represented by 1-byte Type, 1-byte Length, and 2-byte CIDinformation, having a total of 4-bytes of information. Compared to theconventional CID update information, the Old_CID_BITMAP 33 includes abitmap field 331 indicating whether second CIDs are allocated or not fortheir corresponding first CIDs, thereby reducing the size of the firstCID information.

Now a description will be made of an example of configuring the new CIDupdate information according to the present invention with reference toFIG. 1.

The old BS 100 manages the CIDs 138, 239 and 23 corresponding to thethree respective services 10, 65 and 121. As the MS moves from the oldBS 100 to the new BS 200, it registers to the new BS 200. During a CIDupdate operation in the registration, the new BS 200 need not toallocate a new CID for the service 65 because the new BS 200 cannotprovide the service 65 with the first CID 239 or the MS does not need toreceive the service 65.

The new BS 200 then configures the Old_CID_BITMAP area illustrated inFIG. 3 in order to configure the new CID update information. The new BS200 arranges the first CIDs 138, 239 and 23 in a predetermined order(i.e. ascending or descending order) of CID value and sets bit valuesfor the arranged first CIDs to allocation or non-allocation in a binarybitmap. Specifically, the new BS 200 arranges the first CIDs 239, 138and 23 in this order, maps the arranged first CIDs to bits starting fromthe LSB in one to one correspondence, and sets bits for the first CIDsof the services 138 and 23 each to 1 and a bit for the first CID of theservice 239 to 0. As a result, the bitmap value is “011”. In “011”, “0”corresponds to “239”, “1” to “138” and the last “1” to “23”.

The new BS 200 must allocate new CIDs for the second and last “1” bits.In FIG. 1, the new CIDs are “4” and “124”. Thus, “124” corresponding tothe last “1” is mapped in the Value field of the New_CID 35, and “4”corresponding to the second “1” is mapped in the Value field of theNew_CID 37. While the new CIDs are mapped sequentially in the orderstarting from the LSB, it is obvious that the new CID mapping can becarried out in the order starting from the MSB.

FIG. 4 is a flowchart illustrating a CID updating method between a BSand an MS in the BWA communication system according to the presentinvention.

Referring to FIG. 4, upon receipt of a registration-request (REG-REQ)message in step 401, the new BS arranges first CIDs allocated to the MSby the old BS in a predetermined order (for example, according to theCID values) in step 403. The new BS determines whether an arranged firstCID can be updated in step 405 and determines whether a second CID hasbeen allocated with respect to the first CID in step 407. If a secondCID is allocated, the procedure goes to step 409, otherwise it goes tostep 411. The second CID is a value that the new BS sets randomly. Thatis, the new BS creates connections for available services consideringits resource state, determines new CIDs for the available service, andnotifies the MS of the new CIDs in a CID updating procedure.

In step 409, a bit value corresponding to the first CID is set to 1 inthe Value field of the Old_CID_BITMAP area. In step 411, the bit valuecorresponding to the first CIDs is set to 0 in the Value field of theOld_CID_BITMAP area. The new BS maps bit values sequentially startingfrom the LSB in the Old_CID_BITMAP area in step 413. Steps 405 through411 are repeated until the first CID mapping is completed.

In step 415, the new BS encodes second CIDs corresponding to 1s in theOld_CID_BITMAP in the TLV format, thereby generating CID updateinformation. The CID update information is transmitted to the MS by aregistration-response (REG-RSP) message for the REG-REQ message.

For accurate mapping between first CIDs and second CIDs, the first CIDsare arranged according to a criterion preset between the MS and the BS,such as CID value.

In accordance with the present invention as described above, a new BSencodes at least one CID allocated to an MS by an old BS to becompressed to a bitmap and creates new CIDs according to the bit valuesof the bitmap. Therefore, the amount of CID update information that theMS receives at a handover is reduced and, as a result, the useefficiency of radio resources is increased.

While the invention has been shown and described with reference to acertain preferred embodiment thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

1. A Base Station (BS) in a Broadband Wireless Access (BWA)communication system, comprising: a receiver configured to receive aregistration request (REG-REQ) message from a Mobile Station (MS); and atransmitter configured to transmit a registration response (REG-RSP)message to the MS, wherein the REG-RSP message includes identifier (ID)update information including a bitmap area and a new ID area, the bitmaparea indicating whether at least one ID corresponding to at least oneservice is updated, and the new ID area including at least one new IDcorresponding to a predetermined bit value in the bitmap area.
 2. The BSof claim 1, further comprising: a processor configured to configure theREG-RSP message after reception of the REG-REQ message.
 3. The BS ofclaim 2, wherein the processor arranges the at least one IDcorresponding to the at least one service in a predetermined order,determines whether the at least one new ID is allocated to update the atleast one ID corresponding to the at least one service, sets the atleast one bit value in the bitmap area according to the determination,and configures the REG-RSP message by including the bitmap area and thenew ID information when at least one bit value in the bitmap areaindicates that the at least one new ID is allocated to update the atleast one ID corresponding to the at least one service.
 4. The BS ofclaim 3, wherein the predetermined order is one of an ascending order ofvalue of the at least one ID corresponding to the at least one serviceand a descending order of the value of the at least one ID correspondingto the at least one service.
 5. The BS of claim 3, wherein the processorsets the at least one bit value sequentially starting from a leastsignificant bit (LSB) of the bitmap area according to whether the atleast one new ID is allocated.
 6. The BS of claim 3, wherein theprocessor sets the at least one bit value sequentially starting from amost significant bit (MSB) of the bitmap area according to whether theat least one new ID is allocated.
 7. The BS of claim 3, wherein theprocessor sets the at least one bit value to 1 at a predetermined bitposition in the bitmap area, when the at least one new ID is allocated,and sets the at least one bit value to 0 at the predetermined bitposition in the bitmap area, when the at least one new ID is notallocated.
 8. The BS of claim 1, wherein the ID corresponding to the atleast one service is a service flow ID and the new ID is a Connection ID(CID).
 9. The BS of claim 1, wherein at least one bit among bitsincluded in the bitmap area indicates a length of the bitmap area. 10.The BS of claim 1, wherein the number of the at least one new ID isequal to the number of the predetermined bit value indicating that thenew ID is allocated to update the at least one ID corresponding to theat least one service among bit values in the bitmap area.
 11. A MobileStation (MS) in a Broadband Wireless Access (BWA) communication system,comprising: a transmitter configured to transmit a registration request(REG-REQ) message to a Base Station (BS); and a receiver configured toreceive a registration response (REG-RSP) message from the BS, whereinthe REG-RSP message includes identifier (ID) update informationincluding a bitmap area and a new ID area, the bitmap area indicatingwhether at least one ID corresponding to at least one service isupdated, and the new ID area including at least one new ID correspondingto a predetermined bit value in the bitmap area.
 12. The MS of claim 11,wherein the at least one bit value is set to 1 at a predetermined bitposition in the bitmap area, when the at least one new ID is allocated,and the at least one bit value is set to 0 at the predetermined bitposition in the bitmap area, when the at least one new ID is notallocated.
 13. The MS of claim 11, wherein the ID corresponding to theservice is a service flow ID and the new ID is a Connection ID (CID).14. The MS of claim 11, wherein at least one bit among bits included inthe bitmap area indicates a length of the bitmap area.
 15. The MS ofclaim 11, wherein the number of the at least one new ID is equal to thenumber of the predetermined bit value indicating that the new ID isallocated to update the at least one ID corresponding to the at leastone service among bit values in the bitmap area.